This application claims the benefit of provisional patent application No. 60/545,459, filed Feb. 17, 2004.
The field of the invention pertains to diesel engines with pressure sensors adapted to directly measure individual cylinder pressures in real time.
Diesel engines can significantly benefit from cylinder pressure-based controls resulting in reduced harmful emissions, better fuel economy and drivability, and lower engine noise levels. Recently, as much as a 24% reduction in soot emissions and a 12% reduction of NOx emissions were demonstrated by a closed loop control of fuel injection timing and duration based on information provided by pressure sensors located in all engine cylinders. In passenger car and light duty truck engines, where glow plugs are used, a preferred way of introducing a cylinder pressure sensor into a combustion chamber is through a glow plug.
Applicant's fiber optic pressure sensors have been successfully used to measure the dynamic component of the combustion engine cylinder pressure. In the existing design based on two fibers applicant's sensor compensates for such error sources as LED temperature and aging effects, photodiode thermal dependence, fiber to LED/photodiode coupling dependence on temperature, as well as low frequency fiber bending. However, the current sensor only responds to the dynamic component of total cylinder pressure. Furthermore the present design does not compensate for light intensity changes associated with rapidly occurring fiber bending.